Nightsbane, you got a lot of really good advice here, but I think Rionna gave you the best of all, go find a large empty parking lot and practice, practice and then practice some more. Just about anybody can fly down the straightaway, it's the slow speed turns and the starts and stops that most riders need to work on. You'll find your groove through lots of repetitions and one day you will realize that you probably can't remember the last time you had that "jerky" feeling.
I can't speak for anybody else, just me, but even though I rode dirt bikes every day as a kid, it took me a good while to feel solidly in control of a street bike when I started riding again after 20+ years of not riding. I think the GZ is one of the very best choices for someone to learn to ride on. It handle well, doesn't really have enough power to get away from you easily, and it's light enough to pick up if you fall over.
I saw a young lady on a big Harley touring bike take a spill at a stop sign the other day because she hit a little gravel and once it started to go, she didn't have the strength to keep it up. I think she probably hurt her hip trying to keep it from falling over. She was almost completely stopped when it dropped her and it took two big men to get that puppy back upright.
You've got the right bike, just get out there and spend a lot of time practicing slow speed maneuvers and stops and starts.
